Combine sausage and onion in large skillet. Cook over medium-low heat, stirring occasionally, until sausage is browned (& cooked through) Stir in flour; mix well, allowing it to absorb the drippings from the sausage.
Stir in evaporated milk, water, salt and hot pepper sauce, stirring constantly, until mixture comes to a boil. Cook for 1 to 2 minutes, until thickened.